Terminal structure for electric lamps



Feb. 1 1942- c. A. COTMAN ETAL TERMINAL STRUCTURE FOR ELECTRIC LAMPSFiled July 12, 1941 Inverfiors Cart A. Co kman, Daniel K. Wright bW WTheir- A't'tor-neg.

Patented Feb. 10, 1942 TERMINAL STRUCTURE FOR ELECTRIC LAMPS Carl A.Cotman, Parma, and Daniel K. Wright, Cleveland Heights, Ohio, assignorsto General Electric Company, a corporationof New York Application July12, 1941, Serial No. 402,121

7 Claims.

Our invention relates to electric incandescent lamps and similar devicescomprising a bulb having an electrical energy translation element sealedtherein and a. base mounted on said bulb. More particularly, ourinvention relates to a base or terminal structureespecially suitable fordevices such as described and claimed in United States Patents Nos.2,148,314 and 2,148,315, issued February 21, 1939, to D. K. Wright.

One object, of our invention is to provide a base or terminalarrangement for electrical devices of the above type which is simple inconstruction and very inexpensive, and which is firmly secured to thelamp envelope by mechanlcal means Another object of our invention is toprovide an electrical device having a base or terminal arrangement whichextends over the exhaust tip of the lamp envelope so as to form aprotective shield or guard therefor serving to protect the exhaust tipfrom external shocks or blows which ordinarily might result in theaccidental breakage oi the exhaust tip with conseuuent destruction ofthe lamp itself.

Further objects and, advantages of our inven tion will appear from thefollowing description cl 2. species thereof and from the accompanyingdrawing in which:

l isle side elevation, partly in section, oi electric incandescent lampprovided with a terminal arrangement according to our lnventiorl; Fig. 2a fragmentary rear elevation or" the base portion of the lamp shown inFig. i; Fig. 3 is a fragmentary perspective view of? the base portion ofthe lamp shown in l; is fragmentary "view. on an enlarged scale, of thelamp envelope and base in position for assembly.

Referring to the drawing, the invention is there shown in connectionwith an electric in candescent projector lamp of the sealed beam typesuch as described and claimed in the above mentioned patents. The lampcomprises a sealed glass bulb or envelope ill consisting of a preformedpressed glass concave reflector section it of heat-resisting glass, anda cover glass or lens section l2, also of heat-resisting pressed glass,sealed together by fusion. The interior surface I3 of the reflectorsection I l is of any suitable shape, preferably that of a paraboloid,and is covered with a reflecting metallic coating l4, preferablyaluminum, so as to form a reflecting surface. Mounted within theenvelope Ill, in definite optical arrangement to the focal point of thereflecting surface thereof, is an electric energy translation element orfilament l5, preferably in the form of a linear coil of suitablemetallic refractory material, such as tungsten. The filament issupported within the bulb ill by, and electrically connected at its endsto, a pair of relatively heavy rigid leading-in wires l6,-|| whichextend through openings IS in the reflector section to closed metal cupsor thimbles I 9 having their edges or rims fused to and sunk andembedded in the thickness of the glass surrounding the openings H, thethickness of the glass at such points being increased by the provisionthereat of glass bossesv 20 on the exterior surface of the lampenvelope. At their outer ends, the metal cups l9 are provided withtubular outward extensions or projections 2| (Fig. 4) of reduceddiameter and closed at their outer ends, into which projections theleading-in wires I8, I! extend and are secured by suitable means, suchas by solder 22, so as to provide an electrical connection between theleading-in wires endthe metal cups as Well as a farm support for thesaid wires and the filament The metal cups or thimbles it provide aneffective hermetic seal between the leading-in wires and the lampenvelope similar to that de scribed and claimed in United States FatentNo. 2,@98,08u-l3. Wright, issued November 2, 1937. The cups or thiinblesit? are made of a metal to which the glass or the lamp envelope will wetor adhere, and should preferably have an expansion as near possible tothat of glass. For heat-resistant glass of the type known as Pyrex, thecups are preferably made either of iron-nicltei-cobalt alloy known asFernlco, or an iron-nickel alloy containing a proximately l2 per centnickel.

The lamp envelope it is eidiausted and with a suitable gas through anexhaust tube attached to the reflector section it at its vertex, i. e.,at a point between openings 38 so that the exhaust tube is thereforedisposed between the metal thimbles ill. After the gas filling is introclucedinto the lamp envelope, the exhaust tube 23 is tipped oil toprovide a flattened exhaust tube 24, as shown in the drawing. Theflattened exhaust tube tip it is disposed vin a plane substantiallycoinciding with the plane passing through the axes of the metal thimblesI 9.

Mounted on each of the metal cups or thimbles i9 and firmly securedthereto, is a metal contact lug or terminal member 25 which togetherform the base or terminal structure of the lamp. The terminal lugs ormembers 25 each consist of a strip of metal having lamp attachmentportions 26 extending transversely across the rear of the lamp envelopeand the outer ends of the metal thimbles l9, 1. e., at right angles tothe axis of the reflector section ii, and rigidly secured to the metalcups or thimbles [8. For this latter purpose, the said portions 26 areprovided with inturned eyelets 21 which fit over the tubular extensionsor teats 2| on the metal thimbles l8 and are firmly secured thereto in asuitable manner, such as by soldering.

The terminal lugs 25 are mounted on the metal thimbles I! with theattachment portions 26 thereof extending towards and in alignment witheach other, as shown in Fig. 2, so as to overlie the lamp exhaust tubetip 24 which is disposed between the metal thimbles I9. In this manner,the terminal lugs 25 form a protective shield or guard for the exhausttube tip 24 serving to prevent the latter from being subjected toimpacts or shocks which might cause its breakage. The inner facing ends28 of the terminal lugs are, however, spaced a slight distance apart soas to prevent the contacting thereof and resultant short-circuiting ofthe lamp terminals.

To prevent interference between the flattened exhaust tube tip 24 andthe overlying portions of the terminal lugs 25, the inner facing ends ofthe latter are provided with opposed notches 29 which together form asuitable recess for the accommodation therein of the flattened exhausttube tip 24 should the latter extend far enough out from the lampenvelope to normally interfere with the terminal lugs. The notches 29,in effect, result in the formation of protective ears '0 on the contactlugs 25 which ears form the protective shield for the exhaust tip 24.

At their outer ends, the metal strips 25 constituting the terminal lugsare preferably bent towards the lamp envelope at a suitable angle lessthan 90', such as say 45 or thereabouts, to form angular portions 3| inwhich suitable binding screws 52 are threaded for the purpose offastening the current supply wires 55 from a source of power. Thecurrent supply wires 33 may be fastened to the terminal members 25 bymeans of conventional connector lugs 34.

The outermost end portions of the terminal lugs 25, beyond the angularportions 3! thereof, are further bent towards the lamp envelope in adirection substantially at right angles to the transversely extendingattachment portions 26, i. e., in a direction longitudinally of the lampreflector axis, so as to form bracing leg portions 25. The free edges 56of the said bracing leg portions 35 rest on the convex rear surface 31of the lamp envelope so as to brace the terminal lugs 25 and therebyprovide a firm mounting of the same on the lamp. I'he edges 36 of thebracing legs 55 are preferably made of a concave shape of greatercurvature than that of the convex rear surface 51 of the lamp envelope,in order that each edge may engage the said surface 21 at two spacedpoints, that is, at the opposite ends of each edge 36, thus providing abetter and firmer support for the terminal lugs.

The terminal lugs 25 are preferably punch d, from a strip of metal ofthe desired width and thickness. To effect a material saving in themetal stock out of which the terminal lugs are formed, the extreme endportion of the bracing legs 35 are preferably made of reduced width andof the same configuration as the notches 29, as shown at 25 in Fig. 3,so that they may be formed out of the metal which is punched from thenext succeeding terminal member to form the exhaust tip receiving notch29 of such succeeding terminal member.

To prevent vibration of the connector lugs 24 which fasten the currentsupply wires 32 to the terminal members 25, which vibration is otherwiseapt to gradually loosen the binding screws 32, the terminal lugs 25 maybe provided with suitable locking tongues or tabs 2! punched therefromat points adjacent the binding screws 32. The locking tabs 39 extend outfrom the outer surface of the terminal members with their raised freeends 40 disposed closely adjacent the peripheries of the heads of thebinding screws 32. In operation, the locking tabs 28 are engaged by theconnector lugs 34 of the current supply wires and so lock the sameagainst any vibration thereof which might cause the gradual loosening ofthe binding screws.

The improved terminal construction according to the invention is verysimple in construction and inexpensive to manufacture, and besidesproviding adequate protection for the exhaust tip against accidentalbreakage, also provides a base structure of minimum height, i. e., abase which extends a minimum distance out from the surface of the lampenvelope. Such feature thus enables the use of a lamp housing of minimumdepth.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electrical device comprising a sealed bulb having a plurality ofmetal thimbles mounted exteriorly of said bulb, and a terminal structurefor said device comprising a plurality of metal strips secured one toeach of said metal thimbles, each of said metal strips having an endthereof abutting against the surface of said bulb.

2. An electrical device comprising a sealed bulb having a pair of spacedmetal thimbles mounted exteriorly of said bulb and an outwardlyextending exhaust tube tip disposed substantially between the said metalthimbles, and a terminal structure for said device comprising a pair ofmetal strips secured one to each of said metal thimbles and extendingtowards each other so as to substantially overlie said exhaust tube tipand thereby form a protective shield therefor.

3. An electrical device comprising a sealed bulb having a pair of spacedmetal thimbles mounted exteriorly of said bulb and an outwardlyextending exhaust tube tip disposed substantially between the said metalthimbles, and a terminal structure for said device comprising a pair ofmetal strips secured one to each of said metal thimbles and extendingtowards each other so as to substantially overlie said exhaust tube tipand thereby form a protective shield therefor, the facing edges of saidmetal strips being slightly spaced from each other and having opposednotches forming an enlarged recess for the accommodation of the saidexhaust tube tip therein.

4. An electrical device comprising a sealed bulb having a pair of spacedmetal thimbles mounted exteriorly of said bulb, the outer ends of saidmetal thimbles having a cylindrical extension. and a terminal structurefor said device comprising a pair of metal strips secured one to each ofsaid metal thimbles, each of said metal strips having an eyelet fittingover the said cylindrical extension on the associated metal thimble andbeing secured thereto.

5. An electrical device comprising a sealed glass bulb having a convexouter wall portion, a

plurality of spaced metal thimbles mounted exteriorly of said bulb, saidmetal thimbles having their edges embedded in and fused to the glassconstituting said bulb, and a terminal structure for said devicecomprising a plurality of metal strips secured one to each of said metalthimbles at the outer ends thereof, each of said metal strips having anend abutting against the said convex surface of said bulb, said endbeing formed of a concave shape of greater curvature than that of saidconvex bulb surface so as to engage the said convex bulb surface at twospaced points.

6. An electrical device comprising a sealed bulb having a convex outerwall portion, a pair of spaced metal thimbles mounted exteriorly of saidbulb, and a terminal structure for said device comprising a pair ofmetal strips secured one to each of said metal thimbles, each of saidmetal strips comprising an attachment portion extending transverselyacross the outer end of the associated thimble and secured thereto, anangular portion bent towards the bulb and provided with means forattaching a circuit connection wire to said angular portion, and abracing leg portion extending substantially at right angles to the saidattachment portion and having its free end abutting against the convexouter wall portion of said bulb tothereby provide an additional supportfor said metal strip.

'7. An electrical device comprising a sealed bulb having a convex outerwall portion, a pair of spaced metal thimbles mounted exteriorly of saidbulb, and a terminal structure for said device comprising a pair ofmetal strips secured one to each of said metal thimbles, said metalstrips extending transversely across and being secured to the outer endsof said thimbles, one end of each of said metal strips being benttowards the said bulb at an angle less than ninety degrees to form anangular portion, said angular portion being provided with means forattaching a circuit connection wire to said angular portion, and saidend beyond said angular portion being further bent into a positionsubstantially at right angles to said transversely extending portions tothereby formbracing leg portions, the free end of said bracing legportions abutting against the said convex outer wall portion of saidbulb to thereby provide an additional support for said metal strip.

CARL A. COTMAN. DANIEL K. WRIGHT.

